This invention relates to a spraying apparatus, and, more particularly, to a spraying apparatus which has a large capacity reservoir and which uses pressurized gas to spray the contents of the reservoir.
It is a common practice to spray materials such as paint and the like with aerosol propellants. An aerosol propellant is stored in a can with the material which is to be sprayed, and the propellant forces the material through a spraying orifice when a valve is opened to atomize and spray the material. Use of aerosol propellants has several drawbacks, however. Aerosol propellants are relatively expensive, and the volume of the container is generally relatively small, usually of a size that can be conveniently held in the hand. Once the can is emptied, it is usually discarded. This not only creates a possible hazard because of any propellant which remains in the can but increases the total cost of the spraying unit.
Spray guns for spraying paint are also available. Spray guns may be operated by pressurized gas rather than aerosol propellants and may have a larger capacity for spraying a larger volume of liquid than an aerosol can. However, spray guns ordinarily require considerable clean-up time when the spraying job is completed or when a different material, e.g., a different color paint, is to be sprayed. One advantage of aerosol spray cans over spray guns is that clean-up of reservoirs, hoses, nozzles, and the like is not required.
The invention provides a large-capacity spraying apparatus which is operated by compressed gas. Material which is to be sprayed is contained in a cartridge which is removably positioned in a pressure chamber, and an aerosol-type valve and spraying nozzle are mounted on the cartridge. When the job is completed or a different material is to be sprayed, the cartridge is merely removed from the pressure chamber and replaced with another cartridge. The material is sprayed by compressed gas, e.g., air, and expensive aerosol propellants are not needed. Further, the pressure of the gas within the apparatus may be relatively low, e.g., less than 100 psi to reduce the potential hazard of using a pressurized vessel. When the spraying apparatus is not being used, neither the pressure chamber nor the cartridge is pressurized. Partially used cartridges may be sealed and stored for future use, and an empty cartridge may be refilled rather than being discarded.